Minnesota Timberwolves All-Star Jimmy Butler is expected to undergo surgery in the coming days to repair a torn meniscus in his right knee and could return in four-to-six weeks, league sources told Yahoo Sports.

A final timetable will be set after the procedure, league sources said.

An MRI on Saturday revealed the injury after X-rays were taken on Butler’s knee Friday night and returned negative. Butler’s non-contact injury early in the third quarter of Friday night’s loss to the Houston Rockets brought concerns about a possible ACL tear, but there was optimism around Butler regarding the final diagnosis.

Jimmy Butler works against Chris Paul on Friday night. (Getty Images)

Minnesota is 36-26 and holds the fourth seed in the Western Conference but now faces an extended absence for Butler.

Butler, a four-time All-Star, has led the Timberwolves to a resurgent season, averaging 22.4 points, 5.5 rebounds and five assists in 55 games. As a two-way player and stalwart for coach Tom Thibodeau, Butler is also is averaging a league-high 37.3 minutes per game.

Butler joined the Timberwolves as part of a trade from the Chicago Bulls on draft night last June.